Carburetor



NOV. 7, 1933. C. F JOHNSON 1,934,268

` CARBURETOR Filed Sept. l0, 1950 3 Sheets-Sheet 1 @fum Nov. 7, 1933.

c. JoHNsoN 1,934,268

CARBURETOR I Filed Sept. 10, 1930 5 Sheets-Sheet 2 Nov. 7, 1933. r

c. F. JCHNsoN 1,934,268

CARBURETOR Filed Sept. lO. 1930 3 Sheets-Sheet 3 Er @kwwm Patented Nov. 7, i933 UNITED STATES ,CABBUBENB Chester F. Johnson, deceased, late of Detroit,

Mich.. by Detroit and Security x Trust Detroit, Mich., now by change of name, Detroit Trust Company, executo application september lo. lazo serai No. 481,024

2 Claims. (CL 261-64) This invention relates to improvements in carburetors for internal combustion engines and has e special reference to an improved fuel supply and metering system, particularly suitable for downdraft carburetors.

It is an object of this invention to provide an improved and simplified carburetor of the class described wherein the fuel delivery nozzle is subjected to substantially manifold suction regard- 1 las or the throttle position. This result ls aecomplished by eliminating the use of a Venturi or choke tube and so forming the air passages about the fuel nozzle asto subject the latter to increased suction due to a change in direction of the air stream.

It is another object of this invention to provide a fuel feeding system wherein the fuel is metered both at the entrance and exit of a fuel passage,

the entrance of which is submerged in fuel, and to provide manually and thermostatically controlled air bleeds into the passage between the metering orifices, thus varying the effective suction on the entrance or submerged fuel meteri118 orifice.

It is also an object of this invention to provide an improved carburetor vincorporating a thermostatically modied accelerating device adapted to reserve a supplemental or follow-up fuel charge prolonging-the period` of accelerating mixture quality until manifold conditions become stabilized at-the increased rate of flow.

It is still another object of this invention to provide an improved air valve control wherein a choke-control applies a secondary spring pressure of a materially dierentbuild up to hold the air valve nearly closed for starting purposes,- together with means for limiting the positive closing of the air valve by the choke control.

Other and further important objects of this invention will become apparent from the following description and the accompanying drawings.

This invention (in a preferred form)' is illustrated in the drawings and hereinafter more fully described.

On the drawings:

Figure 1 is a side elevation of a carburetor elnbodying one form of the features of lthis invention.

Figure 2 is a cross-section through the carburetor in a plane parallel to Figure 1, with the air bleed structure turnedrinto the plane of the section.

uri

e 3 isa section on the line III-111 of Fig- Figure 4 is a section on the-line IV--IV of Figure 3.

Figure 5 is a diagrammatic layout` of the various fuel passages with the exception` of the. fuel supply to the stabilizer well.

Figure 6 is a fragmental perspective view of the choke control. 1 f e As shown on the drawings: 4

The carburetor of this invention is of the downdraft type wherein a vertical mixture passage 10 discharges downwardly past a throttle valve 11 to a mounting flange l2.' The mixture passage is substantially unrestricted' by the equivalent of a Venturi or strangle tube since it has been found. that the arrangement to be de- 7 scribed eliminates the necessity of 'such a restriction to produce the required suction on the fuel discharge orifice. The carburetor lbody 13 `proper contains the mixture passageioand an air inlet passage 14 thereto whichl makes juncture with the mixture passage at arr-abrupt angle to take advantage of the increasedzsuction available due to air flow deflection ,at the inside radius of the elbow so formed. A fuel dlsonergenozzle l5 is located at this pomtond $0.1

is fed through the passages 16 andi'l froma oat bowl 18 formed. as part of a cover member 19 attached beneath the air inlet passage in the body 13.v

The oat bowl is the cover and a'needle valve 21 engagesra seat 22 therein the needle valve resting on va plug A 23 screwed into the hinged float24 and hence is readily adjustable to vary the fuel level in the float chamber.

Fuel from the float bowl enters the-passage 17 in a central boss 25 and is metered through a submerged orifice 26 therein. Both the orifice 26 and the nozzle l5 are of a capacity so large that the mixture would be very much too rich if it were 9.5 not thinned out by means of an air bleed which enters through a passage 21 above the normal fuel level. The amount of the air bleed is qualifled to produce the desired mixture quality under different driving conditions by means of an economizer tube 28 normally covered by a pad 29 carried by a lever 30 which lever is lifted by a cam 31 on the throttle shaft 32 to open the entranceto the economizer tube. The passage 27 also has a constant air bleed port 33 controlled by an adjustable needle valve 34 so that a suitable adjustment of the cam 31 on its shaft causes closing of the economizer tube 28 at full throttle when maximum power is desired and-under these conditions an adjustment of the needle valve 34 no provided with an inlet 20in 35. l

conditions.- As the throttle is turned towards the closed position the cam 31 pushes the lever 30 away from the end oi the tube 28 which pei-mits additional air to reach the passage 27, the amount of which is determined by calibration oi the tube 128. The position of thecam is adjustable on the-throttle shaft and determines the transition point between the economical and power ranges relative to throttle opening.

For purposes of calibration at lower speeds full throttle, in addition to the air valve adjustment to be described, the upper and lower orifices 15 and 26 can be varied. The upper oriiice is normally several sizes larger than the lower one and if it were desired to make the mixture richer at lower speeds a still smaller lower nozzle would be used, and to perhaps also increase the size of the upper oriiice. These operations would be reversed to thin out the mixture.

The air inlet passage 14 is fed through an air valve port 35 regulated by a hinged airvalve 36. The valve is urged towards itsseat by a spring 37 having an adjustable anchorage 38 which can be retracted by a nut 39 engaged by a spring urged detent 40. No primary air supply is prox vided, idling quality o f the mixture being obtained by having the air valve floating off its seat as controlled by the tension of the spring 37.

The air valve is stabilized or damped to avoid fluttering by providing a closed well 41 containing a loosely fitting stabilizer plate 42 hooked to the air valve by a rod 43 passing up through a tube 44. 'Ihe well 41 isillled fromthe nozzle passage 16 through a-small` hole 45 shown in dotted lines in Figure 3, it being diiiicult to show n this hole "in elevation in any of the other iigures.

By so lling the well the length thereof can be materially shortened .since the well when once filled wlllremain full regardless of the level of fuel in the float bowl and the highest positionof the plate4 is not limited by the fuel level. Also greater clearance between ythe plate and the well is thus permissible, so that no trouble will be caused by sediment, which will settle below the plate and remain undisturbed thereafter.

A-starting control acts to build up additional springv pressure on the air valve to increase the resistance against more than a minimum opening thereof. 'Ihis additional pressure is preferably of a different and more abrupt character to facilitate choking the air supply and is arranged as follows: A stub shaft 45 carries a lever.46 on its inner end, which lever can be elevated to engage beneath'the air valve. This lever carries an offset lug 47which is aligned with an adiusting screw 48 which acts to prevent complete closing of the air valve by the lever. The outer end of the shaft carries a second lever 49 clamped thereto, and an operating lever 50 is free on the shaft, being connected to the lever Y 49 by a torsion spring 51 so that a clockwise movement of the lever 50 imposes spring pressure on the lever 49 tending to elevate the inside lever 46 into yielding contact with the air valve.4 With this arrangement a suitable dash controlY hooked up to the lever 50 will act to bring into action the spring 51 to supplement the normal air valve spring to enrich the mixture to the extent required to idle a cold engine.v The torsion spring has an entirely different build up from the normal air valve spring, thus greatly increasing the load on the valve. In order to still further increase the richness of theV starting mixture. the lever 49 is provided with a lug 52 so disposed as to be struck by an arm 53 on the operating lever 50, the arrangement being such that an extreme movement of the lever 50 holds the inside lever 46 rigidly against its stop screw 48. thus` restricting the air valve to a deilnite amount of opening regardless of suction.

Accelerating mixture quality is obtained by momentarily raising the air pressure in the float chamber. This is accomplished by providing an air pump cylinder 54 containing a throttle operated piston 55, the cylinder discharging into a passage 56 leading to the, float bowl. The capacity of the pump is made much too large for normal temperature operation and is qualiiied to meet the different temperature requirements by means of a temperature responsive element 57 operating on an atmospheric vent 58. The passage 56 is also provided with a small xed vent 59 which serves as a normal iloat bowl vent and reduces the pump pressure at slow throttle open- 100 ing rates when accelerating mixture quality is not required. The two vents 58 and 59 are much lower than the outlet of the nozzle 15 so that in the event of iiooding from any cause, very little if anyyfuel would ow to the motor but would escape through the vents into a catch basin 60 from which it could be drained to a point of safe The momentary increase in pressure in the float bowl, due to operation of the air pump, not 110 only momentarily increases the fuel flow from the fuel nozzle 15- but also delivers fuel through a calibrated tube 61 to a pocket 62 from which a. tube 63 delivers the fuel to the air inlet e. This structure provides a prolonged accelerating charge after the'excess pressure on the oat bowl has dissipated, and the rate of this`supplementalor prolonged ilow can be regulated by a suitable calibration of the tube 83 while the duration of the ow can be regulated by a suitable calibration of the tube 61.

In some engine installations it has been found that improved manifold distribution is obtained by providing a iln 64 in the angle of the junction of the airinlet and mixture es, a second n 65 being positioned on the air valve to cooperate with lthe nrst mentioned nn when the air valve is opened. Y

In the operation of this carburetor, the richer mixture required for starting a cold engine is obl iuel nozzle, an extreme or locking movement of the lever being -required only under very adverse conditions. The lever adjusting screw 48 prevents complete closing o! the air valve by the choke control and is adjusted to provide sumcient air for idling a cold engine, this screw preventing the complete stoppage of air flow except for the nozzle air bleed, since no other primary air supply is provided.

Thei'uelfeedtothe nozzle 15 is limitedbythe submerged orifice 26 which gives a constant now except during increases in the air pressure in the float bowl, or at extreme suction demands which change the submerged character of the orifice. 'I'he fuel passage is located in the center of the iloat bowl and extends vertically until considerably above the fuel level, thence in an upwardly sloping direction to the point of delivery, so that the quality of the mixture is subjected to a minimum amount of variation due to inclination of the vehicle.

The mixture quality is materially affected by the air bleed into the fuel passage. a small adjustable lbleed serving for cold conditions while a supplemental bleed is provided by the thermostatically controlled port. The mixture outlet point at the inside radius of the bend has been found to be a nearly ideal location since the suction at the nozzle varies almost directly in step with' the manifold suction and is approximately equal thereto.

The throttle operated accelerating pump is increasingly effective with an increase in the rapidity of movement thereof because of the vent which dssipates the pump pressure at slow rates of movement. Anincreased air pressure in the float bowl discharges additional fuel through the submerged orice and at the same time transfers fuel to the accelerating pocket which fuel is available to sustain the accelerating mixture quality after the pump pressure has -been dissipated.

It will thus be seen that the carburetor improvements described herein produce a greatly improved and simplified structure having important advantages in increased performance and greater simplicity of adjustment over the prior What is claimed as the invention is as follows:

1. In a carburetor,.an air inlet passage and a mixture outlet passage at an abrupt angle thereto, a thin partitionin the angle of the junction of `the air inlet and mixture passages bisecting said passages, a valve controlling the admission of air to said inlet passage, and a n positioned on the outer face of said valve to cooperatewith the said partition when the air valve is open.

2. A carburetor comprising an air inlet passage and a mixture outlet passage at an abrupt angle thereto, a thin partition in the angle of the junction of the air inlet and mixture passages bisecting said passages, a valve controlling the admission of air to said inlet passage, a fm posi-` tioned on the outer face of said valve to cooperate with the said partition when the air valve is open, a metering nozzle discharging into said mixture outlet passage thru the wall thereof adjacent the inside radius of the juncture of said passages whereby the nozzle is subjected to additional suction due to the deflection of the air stream as it changes direction, and means for supplying a fuel and air mixture to said metering nozzle.

DETROIT AND SECURITY v TRUST CO., By CHARLES E. HOWARD,

Trust Ocer, Ezecutor of the Estate of Chester F. Johnson,

Deceased. 

